Piston for internal-combustion engines



ATTORNEYS C. SCHAEFFER PISTON FR INTERNAL COMBUSTION ENGINES Filed May2, 1929 s 471k April 29, 1930.

Patented Apr. 29, ldd@ ran. or ris, rennen, assrenon. ro scontra ANONYMEions Ens nrannrssnrannrs PANHARD a Lnvassoa, or e;

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'lPISTON' FOR NTERNAlL-COMBUSTION' ENGINES Application med May 2, 1929Serial No. 359,947, and in France may 19, 1928.

Pistons of aluminium, which are employed to an increasing degree forautomobile engines on account of their lightness, are disadvantageousdue to the fact that they have a 5 coefficient of expansion which isabout double that of cast iron, and it is, necessary in order to preventthem from gripping 'in the cylinders, to allow a certain play, and thiscauses at slow speed, due to the low temperature corresponding to thisspeed, a disagreeable pounding noise, since the play allowed for thefull speed is too large for the slow speed.

Attempts have been made to give a smaller play to the pistons by acting7against their expansion by means of steel cross members, but thisarrangement has the disadvantage of limiting the expansion to the pointsof junction of these cross members, and these,

under the traction caused by the expansion, may become separated fromthe aluminium shell in which they are imbedded.

@n the other hand, the saidcross members have no useful action upon thebosses in which the end of the piston rod axle is mounted, and there isproduced, due to the expansion of said bosses, a certain play which maybe a source of noise.

The present invention has for its obJect to obviate these drawbacks byallowing the expansion to take place freely. For this purpose, the crossmembers are imbedded in the piston only at one end, ii at all, and theother end, or in some cases both ends, are simply in contact with theinternal wall of the peripheral part of the piston. lt follows that thesaid peripheral wall may expand freely in the circumferential direction,and no gripping is to be feared, since this wall is split and can recedein order to rest upon the free edge of the cross member, which latteronly lslightly expands, so that the withdrawal of the piston wall islimited, and there ,is no danger vof exceeding the elastic limit whichmight put it out of shape.

rlhe cross members are provided at the middle with flanges which areinserted into bosses on the wrist pin, and since their expansion isabout the same as that of the wrist pin, there will be practically noplay at this point.

The accompanying drawing` shows by way p f example various embodimentsof the invenion.

Fig. 1 shows a pistonv in vertical section pasing through the axis ofthe piston rod en Fig. 2 is an external elevational view.

Fig. 3 is a section on the line Hl-Hl of F ig. l.

Fig. 4 is a sectional view on the line lV-llV of Fig. 2. v

Fig. 5 shows a modification of the piston, in section on the axis of thebosses.

Figs. 6 and 7 shows another modification in elevational view andhorizontal section.

ln the upper part of the piston 1 (Figs. 1 and 4) are formed the grooves2 in which the packing rings are disposed as usual. rllhe upper part 1is connected to the lower -part 3 forming a sliding surface, by means ofa support 4 carrying the bosses 5 and 6 in which is disposed the axle ofthe piston rod' end.

y The lower part'3 is separated from the upper part by an annular slot 7and it is also subdivided by vertical slots 8 and 9 which extend as faras the bottom 10 of the iirst slot 2.

llnto the bosses 5 and 6 are inserted the danges formed on the crossmembers 11 and 12. A right-angled end 13 of each ange is imbedded in thelower part 3, whilst the other end 14 forms only an abutment surface incontact with the lower part 3; the holes 15 and 16 are ormed in thebosses and serve to secure the piston rod axle.

ln another embodiment of the invention shown in Fig. 5, the crossmembers 11 and 12 have their ends disposed in the same manner as theends 1d, forming simple abutment surfaces for the lower part 3 of thepiston.

f In another embodiment shown in Figs. 6 and 7, the cross members 11 and12 are connected together at their ends by transverse portions and thusform a combined device, and the contact surface is thus increased;furthermore, to better support the lower part 3, there have beenprovided on the latter the enlarged parts 17 and 18 by which it restsipon the top and bottom of the cross mem- 2 meme@ Claim:

in a piston for internal combustion engines consisting of a metal havinge great eoecient of expansion, cross members of a metal having a smallcoeioient of expansion, these being tted at one end into the peripheralpart of the piston an a. Harige adapted for insertion into the hole inthe boss o the piston adapted to receive the axle o the piston rod end.

n testimony whereof I have hereunto oxed my signature.

CHARLES SCHAEFFER.

